Effects Of Sowing Period And Planting Method On Yield And Quality Of Conventional Indica Rice In Rice Area Of The South Of Henan

Rice is an essential food crop,and the adaptation of rice growth process to temperature and light resources is an important basis for achieving high yield and good quality.The split plot experiment was adopted,and the main plot was set as five sowing periods(15-Apr,30-Apr,15-May,30-May and 14-Jun),and the subplot was two planting methods(seeding raising transplanting and machine direct seeding),which select the representative varieties of conventional indica rice,Huanghuazhan and Meixiangzhan 2,in Pingqiao,Xinyang of Henan Province,China from 2020-2021,through variance analysis,correlation analysis,PCA and Envfit analysis on yield traits and quality indicators.The study investigated the relationship between the temperature and light differences in sowing periods on yield and its components,as well as quality traits such as processing quality,appearance quality,cooking and taste quality,and nutritional quality among two sowing periods.That examined the effects of two planting methods on the yield and quality of conventional indica rice under different temperature and light conditions,in order to offer theoretical assistance for selection of high quality and yielding rice cultivation in appropriate sowing periods in southern rice yield of Henan.The following conclusions were derived from the study.1.There were significant differences in temperature and light resources between five sowing periods during the two years,with little variation between varieties.At the rice nutrient growth stage,the decrease in accumulated temperature of Huanghuazhan was16.11%,drop in accumulated sunshine duration 8.30% and reduced accumulated illuminance 22.47%,while the average decline in accumulated temperature,accumulated sunshine duration and accumulated illuminance of Meixiangzhan 2 was 16.20%,8.09%and 24.19%,respectively.2.Sowing period and planting method significantly influenced conventional indica rice yield and its components between two years.When sowing was delayed,the seeding raising transplanting had the highest yield in second sowing period,with an average yield of 10.06t/hm~2,and machine direct seeding had the highest yield in third sowing period,with 8.50t/hm~2.Seeding rate was the most major factor affecting yield variation during sowing period.The yield of conventional indica rice increased by 1.56 t/hm~2,up to 15.51%,in the seeding raising transplanting compared to the machine direct seeding,with the increase in grain number being the main reason for increase in yield.3.Sowing period and planting method had a significant effect on the amount of plant biomass accumulated in conventional indica rice between two years.Stem leaf and spike dry weights of seeding raising transplanting and machine direct seeding rice showed a general increase and then decreased with delayed sowing,and were higher in second and third sowing periods.The total dry weight of seeding raising transplanting was higher than that of machine direct seeding rice in both the second and third sowing periods,in which the yields were higher.The proportion of stem leaf dry weight was higher than that of spike dry weight was greater at maturity.4.The degree of influence of sowing time and planting methods on various quality indicators of conventional indica rice varies between two years.As the sowing date is postponed,the trend of brown rice percentage,milled rice percentage and whole milled rice percentage for processing quality is generally increasing first and then decreasing,reaching the highest level in the third sowing date.The chalkiness and chalkiness percentage in appearance quality showed a trend of first decreasing and then increasing,with the best performance in the second and third sowing periods.The trend of amylose starch content for cooking and taste quality first reduced and then increased,with the lowest value in the second sowing period,while the trend of protein for nutritional quality was higher in the second and third sowing periods.From the perspective of planting methods,the whole milled rice percentage under seeding raising transplanting is higher than that under machine direct seeding,while the chalkiness and chalkiness percentage are significantly reduced.Moreover,the protein content under seeding raising transplanting is significantly higher than that under machine direct seeding,which is beneficial for improving the partial processing quality,appearance quality,and nutritional quality of rice.The amylose content of the machine direct seeding method is significantly reduced compared to seeding raising transplanting,and the reduction and disintegration values of RVA spectrum characteristic values indicate that the machine direct seeding method performs more stably.The rice produced by the machine direct seeding method has higher taste quality.5.Based on the results of PCA and Envfit analysis,the accumulated temperature and accumulated sunshine duration around 15 d of tillering were the most important climatic response factors for yield and its components,plant biomass accumulation and various quality traits for Huanghuazhan and Meixiangzhan 2 under different sowing periods,with the second and third sowing periods having more sufficient temperature and light resource and high dry accumulation,resulting in the best yields for seeding raising transplanting and machine direct seeding rice,respectively.The seeding raising transplanting and machine direct seeding rice performed well in terms of straight-chain starch content in the second sowing period,brown rice percentage,milled rice percentage and whole rice percentage in the third sowing period,as well as chalkiness ratio,chalkiness percentage and protein content under both sowing periods.In conclusion,temperature and light differences conditions varied greatly between sowing period and were closely related to yield and components,plant biomass accumulation and various quality indicators.The essential factors influencing the yield differences between sowing periods and planting methods were variations in seeding rate and grain number,respectively.Besides,the seeding raising transplanting can optimize some of the processing,nutritional and appearance qualities of conventional indica rice,while the machine direct seeding can improve some of the cooking and taste qualities and achieve superior quality traits in the second and third sowing periods.It is recommended that seeding raising transplanting be applied on 30-April and machine direct seeding be applied from 30-April to around 15-May in the southern Henan rice fields,which will contribute to enhancing and stabilizing the yield and quality of conventional indica rice.